The present invention relates to a method and system of cultivating a rose plant in a greenhouse or a vinyl plastic hothouse so as to obtain cut roses.
A conventional method of cultivating a rose plant will now be described in brief with reference to FIGS. 5A-5E.
When usually 30-40 days have elapsed after a rose seedling is planted, soy bean-sized buds are formed as shown in FIG. 5A. The twigs with these buds and one to two upper leaves thereon are then pinched as shown by broken lines in FIG. 5B. New shoots then come out from the nipped ends of the twigs. However, even if these shoots are grown into twigs, the twigs are too thin and short to be used as twigs with flowers since the mother twigs are thin and have few leaves left thereon. FIG. 5C shows such condition. Therefore, these twigs must be also pinched as shown by broken lines in FIG. 5D. Consequently, twigs with flowers are obtained after twig pinching operations are carried out at least twice, as shown by 5E. However, in an initial period of cultivation of a rose, the length of the twigs cut off is small because many leaves must be left on the stem, or plant foot, of the rose, and high quality cut flowers having a long stem cannot be obtained.
After a first flower-bearing twig nipping operation for flower harvesting is completed, the number of new shoots coming out from the remaining twigs increases. Accordingly, a twig setting operation, in which unnecessary new shoots are removed, has been carried out with much labor, so as to prevent the growth of only such cut flowers that have a small thickness and a small length. When a twig with a flower is cut, two or three five-blade leaves are always left thereon. Consequently, the height of the rose increases gradually, so that the height of the positions for the twig nipping operation in which the twigs with flowers are cut off increases correspondingly, this lowers the efficiency of a twig cutting operation. Therefore, it becomes necessary to reduce the height of the twigs by pruning the same.
The conventional rose cultivating method described above is a rose height increasing tall training method in which the pinching of an upper portion of a twig with a bud and one or two leaves and the cutting of a grown twig with a flower are done with the lower portions of the twigs with the leaves thereon left as they are, to put forth a terminal bud and grow the twig by utilizing apical dominance, that is, the inherent property of a plant such as a rose, whereby a position in which a twig with a flower is cut is heightened. Therefore, it takes much time and labor to remove side buds (lateral buds) and cut a twig with a flower, so that the operation efficiency becomes low. The pruning of twigs is done at least once a year so as to decrease the tree height of the rose, and, therefore, the cutting of a twig with a flower is limited to six or seven times a year at most. The tall training method hampers the passage of sunlight through twigs to cause the unevenness of temperature of the cultivation bed and variations in the environmental conditions in the greenhouse. Since the lengths of stems differ about 20 cm to about 80 cm, much time is required to carry out a flower selection operation (flower grading), and it is necessary that the twigs and buds be thinned out or pinched.